Motors of some electric tools need to have stable output during operation thereof, especially, it is important to keep the motor with a relatively stable rotating speed in the use of the electric tool that requires high power output. For example, in order to obtain a better cutting effect, the speed of the motor needs to be relatively stable when the reciprocating saw is started, if the motor in the process of rotation suddenly fasts or slows rotation speed, which is then easy to cause beating phenomenon of the reciprocating saw. Usually, the reciprocating saw uses a silicon controlled rectifier to achieve the motor's power on and off, rotation speed of the motor is controlled by adjusting the proportion of power on and off times, that is, via duty cycle to adjust the motor's rotation speed. However, the high-speed rotating motor produces an induced electromotive force in an opposite direction to an original direction of the induced electromotive force, the reversing electromotive force will generate an impedance to the power supply when it is turned on again, this impedance makes it impossible to convert electric energy into kinetic energy, and will increase heat generated by the motor. As the motor produces more heat, the electric energy can't be effectively converted into the kinetic energy, so when the motor is loaded, and required torque thereof becomes larger, the speed of the motor will drop rapidly, and when the load decreases, the speed of the motor will be rapidly increased, which will cause the motor output to be unstable, when the reciprocating saw began to cut, it is easy to cause beating phenomenon thereof, and adversely affecting the cutting effect.
Therefore, a new technical program needs to be proposed to solve the above problems.